In general, movable storage devices like multimedia cards (MMC), secure digital (SD) memory cards, compact flash (CF) cards, and memory sticks are used in movable digital devices (i.e. hosts) like camcorders, digital cameras, PDAs (personal digital assistance), and MP3s (MPEG-1 Layer 3). The devices communicate with the hosts in different protocols. Therefore, each movable storage device may only be connected to a host that communicates in a corresponding communication protocol. On the other hand, a smart card that communicates in a corresponding communication protocol form can be connected to a smart card host like a mobile phone.
FIG. 1 is a view illustrating a relationship between conventional movable storage devices and a smart card and corresponding hosts. Referring to FIG. 1, an MMC 12 can be connected to an MMC host 11 and a SD memory card 14 can be connected to a SD host 13. Similarly, a CF card 16 can be connected to a CF host 15 and a smart card 18 can be connected to a smart card host 17.
As previously described, conventional movable storage devices cannot be used in hosts that do not communicate using the same protocol. For example, in order for the MMC 12 to be connected to a PC (not shown), an additional universal serial bus (USB) reader that converts data of the MMC 12 according to protocols used in an USB device (which is a serial interface device used in the PC) may be required. Also, the MMC 12 can support the USB interface, added to an interface controller inside the MMC 12 without having to be equipped with the USB reader additionally. In this case, a method for controlling the MMC 12 to recognize the type of host connected to the device and to make the MMC 12 operate in a corresponding interface mode is needed. In a conventional controlling method, the MMC 12 has an additional pin and the MMC 12 operates in a corresponding interface mode in response to a control signal received from the host through the additional pin. However, the method is inefficient since the MMC 12 has to be equipped with the additional pin and the host has to generate an additional control signal for determining the operation mode of the MMC 12.